xt_state.c revision ccb79bdce71f2c04cfa9bfcbaf4d37e2f963d684 
1/* Kernel module to match connection tracking information. */
2
3/* (C) 1999-2001 Paul `Rusty' Russell
4 * (C) 2002-2005 Netfilter Core Team <coreteam@netfilter.org>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#include <linux/module.h>
12#include <linux/skbuff.h>
13#include <net/netfilter/nf_conntrack.h>
14#include <linux/netfilter/x_tables.h>
15#include <linux/netfilter/xt_state.h>
16
17MODULE_LICENSE("GPL");
18MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
19MODULE_DESCRIPTION("ip[6]_tables connection tracking state match module");
20MODULE_ALIAS("ipt_state");
21MODULE_ALIAS("ip6t_state");
22
23static bool
24match(const struct sk_buff *skb,
25      const struct net_device *in,
26      const struct net_device *out,
27      const struct xt_match *match,
28      const void *matchinfo,
29      int offset,
30      unsigned int protoff,
31      bool *hotdrop)
32{
33	const struct xt_state_info *sinfo = matchinfo;
34	enum ip_conntrack_info ctinfo;
35	unsigned int statebit;
36
37	if (nf_ct_is_untracked(skb))
38		statebit = XT_STATE_UNTRACKED;
39	else if (!nf_ct_get(skb, &ctinfo))
40		statebit = XT_STATE_INVALID;
41	else
42		statebit = XT_STATE_BIT(ctinfo);
43
44	return (sinfo->statemask & statebit);
45}
46
47static bool check(const char *tablename,
48		  const void *inf,
49		  const struct xt_match *match,
50		  void *matchinfo,
51		  unsigned int hook_mask)
52{
53	if (nf_ct_l3proto_try_module_get(match->family) < 0) {
54		printk(KERN_WARNING "can't load conntrack support for "
55				    "proto=%d\n", match->family);
56		return false;
57	}
58	return true;
59}
60
61static void
62destroy(const struct xt_match *match, void *matchinfo)
63{
64	nf_ct_l3proto_module_put(match->family);
65}
66
67static struct xt_match xt_state_match[] = {
68	{
69		.name		= "state",
70		.family		= AF_INET,
71		.checkentry	= check,
72		.match		= match,
73		.destroy	= destroy,
74		.matchsize	= sizeof(struct xt_state_info),
75		.me		= THIS_MODULE,
76	},
77	{
78		.name		= "state",
79		.family		= AF_INET6,
80		.checkentry	= check,
81		.match		= match,
82		.destroy	= destroy,
83		.matchsize	= sizeof(struct xt_state_info),
84		.me		= THIS_MODULE,
85	},
86};
87
88static int __init xt_state_init(void)
89{
90	return xt_register_matches(xt_state_match, ARRAY_SIZE(xt_state_match));
91}
92
93static void __exit xt_state_fini(void)
94{
95	xt_unregister_matches(xt_state_match, ARRAY_SIZE(xt_state_match));
96}
97
98module_init(xt_state_init);
99module_exit(xt_state_fini);
100